Irritable Bowel Syndrome, Digestive Health and Kiwifruit

Professor Giovanni Barbara

Alma Mater Studiorum, University of Bologna, Italy

Roughly 30% of the population is affected by at least one of the several functional gastrointestinal disorders (FGIDs) with functional dyspepsia, irritable bowel syndrome (IBS) and chronic constipation (CC) being the most common. IBS is defined by the presence of abdominal pain or discomfort that is associated with altered bowel habit over a period of at least three months. IBS prevalence in Europe and USA is 10-15% with the constipation predominant IBS subgroup (IBS-C) accounting for approximately 5%. Chronic Constipation (CC) is defined by multiple bowel symptoms that include difficult or infrequent passage of stool, hardness of stool or a feeling of incomplete evaluation. It is a common problem that affects approximately 20% of the world’s population. Both conditions are associated with marked impaired quality of life and significant healthcare burden.

Although the term functional could be interpreted as a synonym of cryptogenetic or idiopathic and patients labelled as neurotic anxious, depressed, otherwise healthy subjects with an imaginary disease, the growing evidence indicating that these are in fact micro-organic diseases and that tailored dietary approaches and therapies can help to improve symptoms is considerably growing. The pathophysiology of FGID incorporates common physiological changes, including GI motor dysfunction, visceral hypersensitivity, psychological components and abnormal central integration of sensory input, the role of diet and other luminal irritants (eg, bile acids, toxins, etc), increased epithelial permeability and mucosal barrier dysfunction, low grade mucosal inflammation and likely a highly probable although not yet clearly identified genetic component. A lot of the current research in the field of FGID has been directed to the potential role of diet, as this has often been recognized by patients a possible trigger of symptoms, and by experts as an opportunity to improve these syndromes with limited costs and side effects.

While restriction diets such as diets low in fermentable olygosaccharides, disaccharides, monosaccharides and polyols (FODMAPS) have been shown to be effective, at least in subgroups of patients with IBS, the described negative effects on the intestinal microbiota (reduced counts of Bifidobacteria and reduction of microbiota diversity) and potential reduction in the total amount of soluble fibres, leading to reduced bulking effect, in patients with constipated bowel habit, raise some concern on the widespread prescription of this type of dietary approaches. On the other hand, dietary fibre supplements have been advocated for the management of CC and IBS-C. Fibre supplementation is effective in increasing intestinal bulk, in shortening intestinal transit times and increasing bowel habit frequency. However, abdominal bloating and distension, flatulence and abdominal pain may limit the use of fibre, particularly in those with abdominal symptoms. On the other hand, soluble fibres accelerate intestinal transit and stimulate the growth of beneficial intestinal bacteria in the colon and have been shown to be effective in IBS-C and CC.

A systematic review showed that fibre supplementation elicited beneficial effects in 5/7 studies in CC and 3/3 studies in IBS-C. Nonetheless data from good quality randomised controlled trials (RCTs) on this approach is limited and larger, more rigorous and long-term RCTs are needed. There are limited data on the supplementation of soluble fibre in the form of fruit. One study compared dried plums vs. psyllium, showing improved defecation frequency during intervention vs. the control period. Anecdotally, kiwifruit is known to promote laxation in people with constipation. Kiwifruit consumption has shown to improve functional constipation in healthy elderly population, according to studies in New Zealand and China. An open, non-controlled and non-randomized longitudinal study was conducted in 46 patients with constipation (Rome III criteria) to whom three kiwifruit per day (green kiwifruit, Actinidia deliciosa var Hayward) were given. The percentage of patients with ≥3 stools per week increased from 82.61% (95% CI: 69–91.2) at week 1 to 97.78% (95% CI: 87.4–99.9) at week 2 of kiwifruit intake, with 76.09% (95% CI: 61.9–86.2) responding during the first week. Another study was conducted in 38 healthy adults aged >60 years, to whom one kiwifruit per 30 Kg body weight for three weeks was given, followed by a 3-week crossover period. This study showed improvement of bowel function. These promising results suggest that the effect of kiwifruit on IBS-C and CC merits further investigation.